Accession No

3678

Brief Description

tell-tale compass, by Robert King, U.S.A., 1840 (c)

Origin

U.S.A.; New York

Maker

King, Robert

Class

navigation; magnetism

Earliest Date

1840

Latest Date

1840

Inscription Date

Material

metal (brass); paper (card); glass; stone (mica)

Dimensions

length 215mm; breadth 185mm; height 100mm

Special Collection

Provenance

Purchased, Tesseract, Hastings-on-Hudson, New York, USA, lot 24, cat. 19., 1987-8.

Inscription

‘ROBERT KING NEW-YORK’

Description Notes

Brass compass mounted in a gimbal ring with a decoratively shaped brass hanger. The dry card is printed with a 64-point compass rose and is mounted to a mica sheet, a paper card, a “jewelled” brass pivot and bar magnet. The original thick glass cover is intact but cracked. In use the compass hangs upside down mounted to the ceiling, traditionally over the Captain’s bunk. Robert King was listed as a mathematical instrument maker at various places in New York between 1812 and 1866.

Complete.

References

Events

Description
Magnetic compass
The magnetic compass consists of a magnetic needle attached to a compass card, graduated into angular points, and is used for navigation. The first known dry pivoted compass is dated as early as 1269.

The compass indicates the direction of the magnetic pole but there are problems caused by the difference between magnetic and true north (true north being the useful reading). The variation between the two must be calculated in order to obtain an accurate reading. True north was sometimes simply offset from the direction of magnetic north, but this did not allow for geographical variation. For this, charts were needed. The iron used in building ships during 19th century also led to problems because the magnetism of iron affected the compasses on board.
18/10/2002
Created by: Saffron Clackson on 18/10/2002

FM:44466